Who loves the sun? Not everyone. Chris Helgren/Reuters

Laws around it date back to Vitruvius, but now city designers can use complex data analytics to build urban spaces around light and shadow.

Our lives may revolve around the sun—quite literally—but the same can’t be said for urban design.

Cities have always reflected societal values; they are a physical reminder of our shared history—from the privileged space offered to churches in medieval

towns to the democratic ideals embodied in Philadelphia’s grid. However, in an increasingly data-driven world, urban designers can now augment traditional approaches with analytical research. This approach is well-established in other fields, and we have seen complex analytics used to understand the impact of environmental factors on retail design, building performance, and health care. Urban designers have only recently started to use these tools, and we can learn a great deal by applying them to the design of sunlight in our public spaces.

Laws to protect access to sunlight date back to Vitruvius, and contemporary versions exist in cities from New York City to London to San Francisco. Ensuring access to sunlight in key public places protects an integral part of what makes these landmark parks and plazas so popular. But as cities grow increasingly dense, access to sunlight becomes a precious commodity.

Many municipalities require that architects prepare shadow impact studies that quantify the impacts of a proposed development on the immediate surroundings. This approach places the emphasis on shadows, rather than on the displaced sunlight. An approach focused on shadows seems counter-intuitive if our goal is to create public spaces that enjoy generous amounts of sunlight. A much better approach would prioritize sunlight and require a process that quantifies and defines the light. By making sunlight the literal “object” of our discussions, designers can then focus on the specific qualities of sunlight, its impact on human behavior, well-being and performance in the urban environment.

We understand intuitively that our behavior is shaped by our surroundings—sunlight being a key driver in how we react to certain environments. The seminal work of William Whyte, author of The Social Life of Small Urban Spaces, documented how people followed the sun throughout the day in New York’s Seagrams Plaza. Whyte observed how people moved from one bench to another and adjusted loose chairs to better track the sun. This is a common phenomenon that plays out on patios, terraces, and parks in cities around the world every day, but one that only recently has started to benefit from an empirical approach that can quantify the value of sunlight.

Behavioral neuroscientists are now focusing their research on the brain’s reactions to various environmental conditions, including Eve Edelstein of Perkins+Will’s Human Experience Lab. Her research on the impact of light spectra on workplace performance pinpoints how different types of light affect an individual’s circadian rhythms and behavior. This research has been primarily applied to workplace design, identifying specific qualities of light suited to particular tasks—even light for work surfaces, bright light for public gathering areas, low-glare light where monitors are used. These techniques have been used to promote creativity, improve test scores, or accelerate recovery time for patients in hospitals.

Stepping out of the workplace, Collin Ellard of the University of Waterloo has conducted similar research into how the human brain and body reacts to different urban settings. Ellard found that varied facades with a high frequency of entrances and articulation satisfy an innate curiosity—engaging people much more than long, uniform facades. That’s why walking ten city blocks can feel quicker than walking only two in a newly built suburb.

But cities are dynamic, ever-changing places, and social media provides another valuable real-time behavioral insight into how people experience urban areas. The Perkins+Will San Francisco studio recently tracked vitality in Oakland using both open-data sources (transit access and population density) and live social media data (Instagram posts and Yelp reviews). The work identified clear spatial relationships between retail and commercial streets and urban vitality, as exhibited by the volume of social media posts, as well as temporal shifts throughout the day and varying light conditions.

Together, these new tools and approaches allow us to respond to sunlight in a more refined way—one that is informed by behavioral science and based on real-time data. This approach would move beyond a binary approach that views all shadows in a negative light, and instead employ the full palette of sunlight that is at our disposal to create spaces uniquely suited to their purpose.

Lower Yonge Precinct Plan (© Chris Foyd courtesy Perkins+Will)

By making sunlight the object of our design, could city builders begin to conceive of entire neighborhoods that accommodate significant development, but also include streets and public spaces that support public health and well-being?

This is an approach used on the Lower Yonge Precinct Plan, a redevelopment plan along Toronto’s waterfront. Computational modeling tools helped identify a central area that receives sun from 10 a.m. to 2 p.m. on the darkest day of the year, December 21. This privileged location was reserved for a public park with development blocks revolving around it—shorter buildings to the south to maintain sun exposure to the park and taller buildings to the north, where they would throw shade onto the Gardiner Expressway. Protecting for this level of sunlight ensures the park can be comfortably used throughout the year. The design of the primary retail street along Harbour Street was established to ensure a minimum of five hours of sunlight on its northern sidewalk between March 21 and September 21, when the radiant heat of sunlight can increase the comfort of shoppers and passersby.

Our streets and public spaces public spaces lie at the heart of our daily lives and deserve the same attention given to our homes, work places, schools and hospitals. Sunlight is a key element in shaping the design of public spaces. We can learn from new innovations in workplace, education, or healthcare design to deliver neighborhoods that support a wide range of economic activity, while also increasing livability and well-being.

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